Field of Invention
This invention relates to a tire pressure control system (TPCS) having a rotatable air passage. In particular this invention relates to a tire pressure control system for measuring the tire pressure on an agricultural vehicle, or machine having a rotatable air passage.
Description of Related Art
In order to improve efficiency and safety on an agricultural machine or vehicle such as an agricultural tractor, it is necessary to change tire pressures depending on whether the tractor is operating in field conditions or on the road. When operating in the field lower tire pressures are required to reduce ground pressure and compaction and to improve the grip of the tires with the earth. For road work, higher tire pressures are required to reduce rolling resistance (which affects the economy of the tractor) and to reduce heat generation (which affects the safety of the tractor). So the tire pressure may vary between 0.6 bar and 2.5 bar.
Generally, every change of the tire pressure requires an interruption of the work operation and also requires further energy when the tire is inflated as the air must be supplied powering air compressors with about 10 kW. In terms of efficiency, it is a vital requirement to provide a TPCS process which is optimized regarding its time to function and its reliability.
Current systems suffer from the fact that the inflation process is not monitored during inflation and the process is only ended when the set value of the tire pressure is reached.
If the TPCS function is interfered by leakages in the system, it is more or less the operator's duty to interrupt the inflation based on his experience and his appraisal if an expected inflation time is exceeded. In this case the inflation process must be aborted due to failure/leakage. This may result in that the inflation process is aborted too early so that the target pressure value is not reached, or that thia inflation process is aborted too late so that energy is wasted in supplying air to a leak or a defected valve.
So current TPCS systems require the driver's attention, concentration and experience to know when an expected inflation time is exceeded else the system is inefficient in that it may continue to supply air to a leak or defect in the system and not be noticed for a period of time.